1. Field of the Invention
The present invention relates to a method and composition for the topical treatment of diabetic neuropathy. More particularly, the present invention relates to a topical composition including a combination of ingredients that provide a surprising degree of effective relief from the symptoms of diabetic neuropathy and to a method for administering the topical composition to treat diabetic neuropathy.
2. Description of the Prior Art
Diabetes mellitus is a common disease that is usually classified into insulin-dependent and non-insulin dependent types. Both types may be managed by diet, in combination with insulin in the first type and a variety of drugs in the second type. However, while the changes in blood glucose associated with diabetes can usually be managed reasonably satisfactorily by conscientious patients and doctors, this does not prevent long term damage to many tissues as a result of the disease. This damage may take many forms but the major types are damage to the eyes (retinopathy), nerves (neuropathy), kidneys (nephropathy) and cardiovascular system.
There are many approaches to reducing or preventing these forms of damage, which are collectively known as the long-term complications of diabetes. One approach is based on damage that results from over-production of the glucose metabolite, sorbitol, in the cells of the body. Glucose can be converted to sorbitol by the enzyme aldose reductase. High levels of sorbitol may be among the causes of diabetic complications such as diabetic neuropathy. As a result, a number of pharmaceutical companies have been developing aldose reductase inhibitors for the purpose of reducing diabetic neuropathy.
It has been established that a wide variety of flavanoids are effective inhibitors of aldose reductase, including such flavanoids as quercetin, quercetrin and myrecetrin. However, U.S. Pat. No. 4,232,040 discloses that despite the fact that these flavanoids have been shown in in vitro studies to be among the most potent flavanoids for aldose reductase inhibition, a need exists for aldose reductase inhibitors that can be more effectively used and in lower doses than the prior art compounds, including these flavanoids.
In fact, numerous patents are devoted to goal of developing improved aldose reductase inhibitors. Among these patents are U.S. Pat. Nos. 6,069,168; 5,011,840; 4,210,667; 4,147,795; 5,866,578; and 5,561,110. Numerous other patents also exist which relate to aldose reductase inhibitors.
Another approach to the treatment of neuropathy is disclosed in U.S. Pat. No. 5,840,736 (Zelle et al.). In this method, pharmaceutical compositions for stimulating the growth of neurites in nerve cells comprising a neurotrophic amount of a compound and a nerve growth factor. These compositions may be administered in a number of ways including orally and topically.
Still another approach to the treatment of neuropathy is disclosed in U.S. Pat. No. 5,550,249 (Della Ville et al.). In this approach, compositions suitable for treatment of vitamin H deficiencies are administered for the treatment of neuropathy. This patent relates to biotin salts with alkanolamines. The compositions may be administered orally, parenterally or topically.
U.S. Pat. No. 5,665,360 (Mann) relates to the treatment of peripheral neuropathies associated with diabetes mellitus by periodic topical application of a composition containing capsicum oleoresin as the active ingredient. When applied to the skin of the affected area, pain and burning associated with the neuropathy are said to be reduced. However, capsicum oleoresin has been shown to kill nerve endings in some cases and thus this composition suffers from this disadvantage.
U.S. Pat. No. 5,981,594 (Okamoto et al.) relates to a method of treatment of diabetic neuropathy using combined administration of a formulation including as an active ingredient, a prostaglandin I derivative with an anti-diabetic agent in order to improve nerve conduction velocities. Suitable anti-diabetic agents include oral hypoglycemic agents and insulin.
The Okamoto patent also contains a detailed discussion of the various types of neuropathy that may be associated with diabetes. According to this patent, nerve conduction velocity (NCV) is the most widely used method of objectively evaluating the severity of diabetic neuropathy. This patent also mentions that current methods of treating diabetic neuropathy such as dietetic therapy, administration of insulin, administration of aldose reductase inhibitors or aminoguaninidine to improve abnormal glucose metabolism, administration of troglitazone or agents for the improvement of blood flow have been tested but found to be insufficient when a single drug was used. Also, according to this patent, methods of treatment by combined use of different therapeutic agents which have different functions had yet to be established. The patent concludes that combined drug therapies for diabetic neuropathy, aiming at recovering once reduced nerve conduction velocity, have not yet been confirmed.
There remains a need in the art for an effective treatment for diabetic neuropathy that does not suffer from the disadvantage that it causes severe side effects, as do many aldose reductase inhibitors, for example.
Accordingly, it is the primary object of the present invention to provide a topical composition that is effective for the treatment of diabetic neuropathy.
It is another object of the present invention to provide a topical composition for the treatment of diabetic neuropathy which does not cause serve side effects in the patients treated with the composition.
These and other objects of the present invention will be apparent from the summary and detailed descriptions of the invention which follow.